Accumulation and precipitation of magnesium, calcium, and sulfur in two Acacia (Leguminosae; Mimosoideae) species grown in different substrates proposed for mine-site rehabilitation

Honghua He, Yaowanuj Kirilak, John Kuo, Hans Lambers
2015 American Journal of Botany  
grateful to Peter Golos and Australian Tree Seed Centre for providing seeds for this research. 8 5 Author for correspondence (honghuahe@ms.iswc.ac.cn) 9 10 2 • Premise of the study: Previous studies showed that phyllodes of Acacia robeorum accumulate much more 1 magnesium, calcium, and sulfur than those of A. stipuligera, and precipitate these elements in phyllodes and 2 branchlets. The substrate in the habitat of A. robeorum was mainly siltstone, having significantly higher 3 concentrations of
more » ... 3 concentrations of plant-available magnesium and sulfur than the sandy topsoil in the habitat of A. stipuligera. It 4 is not known whether the differences in substrates account for the differences in the accumulation and 5 precipitation patterns of magnesium, calcium, and sulfur between these two species. 6 • Methods: Saplings were grown in sandy topsoil or in a topsoil-siltstone mixture proposed for mine-site 7 rehabilitation in a glasshouse. Phyllode magnesium, calcium, and sulfur concentrations of 25-week-old plants 8 were measured. Precipitation of these elements in phyllodes and branchlets was investigated by means of 9 scanning electron microscopy and energy-dispersive X-ray spectroscopy. 10 • Key results: Adding siltstone did not significantly affect phyllode sulfur concentration, but markedly 11 affected magnesium and calcium concentrations in phyllodes of both species. Concentrations of magnesium, 12 calcium, and sulfur in phyllodes of A. robeorum were significantly higher than those in A. stipuligera phyllodes. 13 For both the topsoil and topsoil-siltstone mixture, mineral precipitates were observed in the two species, with A. 14 robeorum having more mineral precipitates containing magnesium, calcium, and sulfur in its phyllodes than A. 15 stipuligera did. 16 • Conclusions: The accumulation and precipitation patterns of magnesium, calcium, and sulfur are more species-17 specific than substrate-affected. 18
doi:10.3732/ajb.1400543 pmid:25667081 fatcat:sqmp3kxhkbbcdcohpqfwjko6m4